If CS4 worked without issue in the past what has changed on your system in the past few days? What version of Windows are you running. I do not thinks its windows NT like CS4 shows. If its Windows 7 see is there is a system restore point you can restore to a point where CS4 was working well.

The latest windows update service pack apparantly ran overnight while my monitor was off and basically bricked it. After system restore all is good for now until Windows wants to update the service packs again... Odd.